The present invention relates to a rotary head type digital signal recording and/or reproducing apparatus, especially to a digital signal recording and/or reproducing apparatus which is suitable for recording and/or reproducing with a variable speed.
As an apparatus for recording and/or reproducing a digital signal with a rotary head, a PCM recorder is known as described, for example, in U.S. Pat. No. 4,594,621. According to the PCM recorder using the rotary head, it is possible to improve a recording density of recording signal, and to provide reproduction with high quality. One of functions of the PCM recorder described above is to provide a long time recording/reproducing and/or a high speed dubbing. Such function can be obtained by varying a number of the rotations of the rotary head and a tape feed speed simultaneously.
In the prior art, in case of varying the number of the rotation of the rotary head, it is also necessary to vary a frequency of a recording signal for maintaining a constant recording density. As a result of varying a frequency, a signal to noise ratio (S/N) is decreased at a low speed because an output of the rotary head decreases at a low frequency of the signal. Also, a S/N ratio is decreased at a high speed because a frequency characteristic of the rotary head deteriorates at a high frequency of the signal.